Results 1 to 3 of 3

Math Help - Completing the square

  1. #1
    Super Member
    Joined
    Dec 2009
    Posts
    755

    Completing the square

    given that (x+b)(x+a)=(x+2)^2-9, find the value of a and b
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2009
    Posts
    806
    Thanks
    4
    Quote Originally Posted by Punch View Post
    given that (x+b)(x+a)=(x+2)^2-9, find the value of a and b
    x^2 + (a+b)x + ab = x^2 + 4x + 4 - 9

    compare the coefficients of x^2, x and constant. Then solve for a and b.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,804
    Thanks
    1577
    It's easier to factorise the RHS using DOTS

    (x + 2)^2 - 9 = (x + 2)^2 - 3^2

     = (x + 2 + 3)(x + 2 - 3)

     = (x + 5)(x - 1).


    What do you think a and b are?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Completing the square.
    Posted in the Algebra Forum
    Replies: 4
    Last Post: September 23rd 2010, 09:51 AM
  2. completing the square
    Posted in the Algebra Forum
    Replies: 10
    Last Post: September 16th 2009, 11:58 AM
  3. completing the square?
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: August 13th 2009, 11:17 AM
  4. Completing The Square
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 4th 2007, 06:18 AM
  5. Completing the Square
    Posted in the Algebra Forum
    Replies: 7
    Last Post: August 31st 2007, 11:36 PM

Search Tags


/mathhelpforum @mathhelpforum